Lighting & Material Interactions Flashcards

A paint specified as NCS S 3040-Y20R appears significantly more orange under warm halogen lighting than under cool daylight. Which property of the paint's pigment formulation causes this?

Answer: A spectral reflectance curve with a steep slope in the orange-red region that amplifies warm light contributions

Paints with steep reflectance curves in warm regions are highly sensitive to the spectral power distribution of the illuminant, appearing more saturated under light-rich in those wavelengths.

Simultaneous contrast can make a neutral gray appear warm or cool depending on its surroundings. In a room, a gray wall flanked by warm-toned wood paneling will appear:

Answer: Cooler and slightly bluer as the eye compensates for the dominant warm surround

Simultaneous contrast causes the eye to perceive the complementary hue of the dominant surround color, pushing a neutral gray toward cool/blue when surrounded by warm amber tones.

A specular highlight on a colored object is typically:

Answer: Near-white or the color of the light source, not the color of the object

Specular reflections for most non-metallic surfaces (dielectrics) are dominated by the light source's color, not the object's pigment, because the reflection occurs before light penetrates the surface.

Which statement best describes how Correlated Color Temperature (CCT) relates to actual light color?

Answer: CCT approximates the apparent warmth or coolness of a light source but two sources with the same CCT can differ in color appearance (Duv)

CCT indicates proximity to the Planckian locus but not the actual chromaticity; the Duv metric captures how far a source deviates from the blackbody curve, explaining why same-CCT LEDs can look different.

When a color expert talks about 'light reflectance value' (LRV) of a paint, they are describing:

Answer: The percentage of visible light the paint reflects, from near 0% (black) to near 100% (white)

LRV quantifies the amount of visible light energy reflected by a paint color, used to assess contrast for safety, accessibility, and spatial perception.

A client's stone countertop looks gray in the store but has a strong green undertone at home. The most likely explanation is:

Answer: The store used a high-CRI neutral light while the client's kitchen has fluorescent lights with a green spectral spike

Many fluorescent lamps have a strong spectral spike in the green region, which can dramatically shift the apparent hue of achromatic or low-chroma materials toward green.

The term 'color inconstancy' in materials science refers to:

Answer: The tendency of a material's perceived color to change as the illuminant changes

Color inconstancy describes how a material's perceived color shifts when the spectral composition of the illuminant changes, a more extreme form of which is observer metamerism.